diff --git a/lib/datastore.js b/lib/datastore.js
index cee6f09..d35f81b 100644
--- a/lib/datastore.js
+++ b/lib/datastore.js
@@ -42,22 +42,25 @@ Datastore.prototype.resetIndexes = function (newData) {
 /**
  * Ensure an index is kept for this field. Same parameters as lib/indexes
  * For now this function is synchronous, we need to test how much time it takes
+ * We use an async API for consistency with the rest of the code
  * @param {String} options.fieldName
  * @param {Boolean} options.unique
  * @param {Boolean} options.sparse
- * @return {Boolean} true if index was created or already exists, false otherwise
+ * @param {Function} cb Optional callback, signature: err
  */
-Datastore.prototype.ensureIndex = function (options) {
+Datastore.prototype.ensureIndex = function (options, cb) {
+  var callback = cb || function () {};
+
   options = options || {};
 
-  if (!options.fieldName) { return false; }
-  if (this.indexes[options.fieldName]) { return true; }
+  if (!options.fieldName) { return callback({ missingFieldName: true }); }
+  if (this.indexes[options.fieldName]) { return callback(); }
 
   options.datastore = this;
   this.indexes[options.fieldName] = new Index(options);
   this.indexes[options.fieldName].insert(this.data);
 
-  return true;
+  return callback();
 };
 
 
@@ -106,7 +109,7 @@ Datastore.prototype.removeFromIndexes = function (doc) {
 /**
  * Update a document in all indexes
  */
-Datastore.prototype.removeFromIndexes = function (doc, newDoc) {
+Datastore.prototype.updateIndexes = function (doc, newDoc) {
   var self = this;
 
   Object.keys(this.indexes).forEach(function (i) {
diff --git a/lib/indexes.js b/lib/indexes.js
index 8022fac..39bd5c8 100644
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -56,7 +56,7 @@ Index.prototype.reset = function (newData) {
 Index.prototype.insert = function (doc) {
   var key, self = this;
 
-  if (util.isArray(doc)) { doc.forEach(function (d) { self.insert(d); }); return; }
+  if (util.isArray(doc)) { this.insertMultipleDocs(doc); return; }
 
   key = model.getDotValue(doc, this.fieldName);
 
@@ -70,8 +70,36 @@ Index.prototype.insert = function (doc) {
 };
 
 
+/**
+ * When inserting an array of documents, we need to rollback all insertions
+ * if an error is thrown
+ */
+Index.prototype.insertMultipleDocs = function (docs) {
+  var i, error, failingI;
+
+  for (i = 0; i < docs.length; i += 1) {
+    try {
+      this.insert(docs[i]);
+    } catch (e) {
+      error = e;
+      failingI = i;
+      break;
+    }
+  }
+
+  if (error) {
+    for (i = 0; i < failingI; i += 1) {
+      this.remove(docs[i]);
+    }
+
+    throw error;
+  }
+};
+
+
 /**
  * Remove a document from the index
+ * If an array is passed, we remove all its elements
  * O(log(n))
  */
 Index.prototype.remove = function (doc) {
diff --git a/test/indexes.test.js b/test/indexes.test.js
index 4d2d3aa..16f62f5 100644
--- a/test/indexes.test.js
+++ b/test/indexes.test.js
@@ -105,6 +105,25 @@ describe('Indexes', function () {
       assert.deepEqual(idx.tree.search('bloup'), [doc3]);
     });
 
+    it('When inserting an array of elements, if an error is thrown all inserts need to be rolled back', function () {
+      var idx = new Index({ fieldName: 'tf', unique: true })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 8, tf: 'world' }
+        , doc2b = { a: 84, tf: 'world' }
+        , doc3 = { a: 2, tf: 'bloup' }
+        ;
+
+      try {
+        idx.insert([doc1, doc2, doc2b, doc3]);
+      } catch (e) {
+        e.errorType.should.equal('uniqueViolated');
+      }
+      idx.tree.getNumberOfKeys().should.equal(0);
+      assert.deepEqual(idx.tree.search('hello'), []);
+      assert.deepEqual(idx.tree.search('world'), []);
+      assert.deepEqual(idx.tree.search('bloup'), []);
+    });
+
   });   // ==== End of 'Insertion' ==== //